1)A 0.5mol sample of He(g) and a 0.5 mol sample of Ne(g) are placed separately in two 10.0L rigid containers at 25°C. Each container has a pinhole opening. Which of the gases, He(g) or Ne(g), will escape faster through the pinhole and why?
A.He(g) will escape faster because the He(g) atoms are moving at a higher average speed than the Ne(g) atoms.
B.Ne(g) will escape faster because its initial pressure in the container is higher.
C.Ne(g) will escape faster because the Ne(g) atoms have a higher average kinetic energy than the He(g) atoms.
D.Both gases will escape at the same rate because the atoms of both gases have the same average kinetic energy.
2)The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.)
A.Na+(g) and Cl–(g)
B.Cs+(g) and Br–(g)
C.Mg2+(g) and O2-(g)
D.Ca2+(g) and O2-(g)
1.Metal-air cells are a relatively new type of portable energy source consisting of a metal anode, an alkaline electrolyte paste that contains water, and a porous cathode membrane that lets in oxygen from the air. A schematic of the cell is shown above. Reduction potentials for the cathode and three possible metal anodes are given in the table below.
A.Early forms of metal-air cells used zinc as the anode. Zinc oxide is produced as the cell operates accordingto the overall equation below.
(i)Using the data in the table above, calculate the cell potential for the zinc-air cell.
(ii)The electrolyte paste contains OH– ions. On the diagram of the cell above, draw an arrow to indicate the direction of migration of OH– ions through the electrolyte as the cell operates.
B.A fresh zinc-air cell is weighed on an analytical balance before being placed in a hearing aid for use.
(i)As the cell operates, does the mass of the cell increase, decrease, or remain the same?
(ii)Justify your answer to part (b)(i) in terms of the equation for the overall cell reaction.
C.The zinc-air cell is taken to the top of a mountain where the air pressure is lower.
(i)Will the cell potential be higher, lower, or the same as the cell potential at the lower elevation?
(ii)Justify your answer to part (c)(i) based on the equation for the overall cell reaction and the information above.
D.Metal-air cells need to be lightweight for many applications. In order to transfer more electrons with a smaller mass, Na and Ca are investigated as potential anodes. A 1.0g anode of which of these metals would transfer more electrons, assuming that the anode is totally consumed during the lifetime of a cell? Justify your answer with calculations.
E.The only common oxide of zinc has the formula ZnO.
(i)Write the electron configuration for a Zn atom in the ground state.
(ii)From which sublevel are electrons removed when a Zn atom in the ground state is oxidized?